Online car sharing and pooling services have been around since there were people online; (TreeHugger here) SpaceShare is a bit different. It is database software for conferences or weddings, customized for the event. For instance, for a wedding, US$ 200 gets you a custom "green travel" website that encourages people to travel together, save money and have someone to talk to on the way. For larger conventions, SpaceShare says "Spending a flight talking to someone about the conference can be a tremendous improvement over flying alone, essentially extending your conference for the duration of everyone's flights." They call it an "environmental networking tool."